The present invention relates to a shoe having at least one base spring element, which is arranged between a heel zone of the shoe and a shaft zone supporting on the cnemial front edge and which expands during a stepping phase.
A shoe of this general type is the object of the as yet unpublished German patent application 101 07 824 2-26 of the applicant of the present invention. According thereto, the shoe is able to store the energy of the momentum that is attained when the shoe is set down in the course of a step and which can release it as efficiently as possible for repelling the foot during a subsequent stepping phase.
The object of the present invention is to further improve the aforesaid effect in a shoe of storing the energy of the momentum attained in the shoe when set down in the course of a step and again releasing it as efficiently as possible for repelling the foot during a subsequent stepping phase.
In the animal kingdom it can be observed that in large running birds—in particular in the stork species—with each step a part of the impact energy is stored in the long tendons so that with the next step it can be again returned. This economical system in nature is not restricted to the large running birds; it is merely particularly obvious in this case. It must rater be assumed, that the tendons and muscular elements of the body in the higher evolved species fulfill the task not only of developing and transmitting power but also the task of storing and returning energy.
It is well known that there is a static load transferring system in the body. In this context this is represented by the sections of the skeleton, including the articulations. In addition, our own studies have shown that there is also a dynamic power developing and load transmitting system. This involves the musculature and the tunica muscularis (fasciae) as well as the tendons, vessels and nerves.
This system, which can also transmit load like bone, has energy storage and release as its third important task.
In virtue of the bones it is not only a question of transfer of an operating force but rather in its structure it represents an element of elasticity, which also stores operating forces partially in its structure so that it can the be released.
If one considers the structure of the foot and the adjacent bones and muscle components, then the following can be established:
At the sole of the foot, impact and pressure zones can be differentiated. Accordingly, the heel represents the essential impact zone. Here upon impact, the major part of the energy is introduced into the osseous system. An artificial storage and release of the energy can occur here as is described in some of the cited patents, through resilient heel constructions. This is only minimally efficient.
In the zone of the forefoot the balls of the foot likewise represent an impact zone. They assume this function when running on the forefoot, but also during the heel-to-toe walking. Here, the operating energy is not only transmitted into the skeletal components. Rather, in virtue of the expansion of tendon and muscular structures, that lie in the longitudinal and transverse sense under the arch of the foot (the so-called plantar aponeurosis), it results in a spring suspension and also in storage of the operating energy in the structures.
In this regard it results especially in an expansion of this tendon plate in the sole of the foot in a transverse direction under the transverse arch of the foot and in the longitudinal direction under the longitudinal arch of the foot. In addition, there is an expansion of the Achilles tendon as well as the muscles that are connected to the Achilles tendon (the suralis and the soleus muscles). Because these muscles in part act via the knee joint on the thigh bones, the entire let is consequently involved in the energy storage. Upon continuing the step, the energy is converted back again into appropriately directed forces, which relievingly support the motor function of the musculature in their force generation.
Upon pushing off, the tendons are relieved and the energy of the stored energy is transmitted into the following step.
Three phases can be differentiated: The first phase results in an elongation and stretching of the tendon structure. This elongation of the corrugated collagen fibers results in a stretching of the fibers. If the stretching is achieved, the fibers cannot be further elongated, which means that then the muscle force is transmitted directly (second phase). The third phase is characterized in that in the next step, at the end, the stored energy, by relieving the tendon structure, is fed back into the new step.
The Achilles tendon and the muscles attached to it as well as the long tendons of the flexors and extensors of the toes and the mid-foot also work according to this principle of energy storage. In a walking or running process, this results in a stressing of these long, cross-articulation tendons and muscle structures. The biasing is transmitted together with the operative muscle force into the next step.
This physiological basic concept is translated according to the invention, in that at least one base spring element is affixed between the heel zone of the shoe and the shaft zone at the cnemial front edge—e.g. minimally biased. The appendage of the base spring element in the zone of the shoe is, according to the invention, upon setting down the heel, moved away from its second appendage on the shaft zone for extension of the base spring element, and especially preferably rearwardly and/or downwardly. The makes possible firstly a greater lever arm for reinforcing the effect according to the invention of the energy storage and release. Secondly, the movement of the tensioning device, already on its own, operates an extension, which advantageously supplements the extension operated by the flexing of the foot during a step.